Retractable wheels

ABSTRACT

An amphibious craft has a hull and wheels for supporting the hull on land. At least one pair of the wheels is driven from a motor on the craft. The driven wheels (13) on one side of the craft are driven independently from those on the other side of the craft. To this end respective drive transmission mechanisms (28, 29, 31; 33, 34) are provided for the wheels to transfer power from the main drive shaft (15) to the wheel stub axles (20). Each drive transmission mechanism is housed in a watertight casing which also acts as the main strut for the wheel when in use. The wheels are retractable into respective compartments in the hull preferably without breaking the strength of the keel.

The present invention relates to retractable wheels and particularly butnot exclusively to a steerable wheel for use in amphibious craft such asa boat adapted to be driven on land. In such a craft the wheel wouldneed to be retractable or easily adjustable for height between a loweredposition in which it would engage the ground for land use and aretracted position.

Whilst amphibious vehicles are not new, most are in the form ofamphibious motor cars (or armoured vehicles). One of the main problemswith this configuration is that the volume of the car is small inrelation to its weight, consequently when in water the vehicle will bedeeply immersed. Having little freeboard the vehicle can easily beswamped in any kind of rough water. There is also an insecurity for theoccupants in being so low in the water. The design of a car is notappropriate for water travel and a speed of only approximately 5 mph ispossible in use. They are nearly always cumbersome on land and sea, arevery slow, and are often designed for military use.

If an amphibious craft is to perform well on water and at higher speedsit must have a hull profiled to make this possible. This willnecessitate the provision of a larger movement of the wheel between theraised position for stowage and the lowered position for road use thanhas hitherto been catered for.

The object of the invention is to provide a retractable wheel designcapable of being applied to provide such a wheel movement.

According to the present invention there is provided a vehicle having asteerable wheel and a mechanism for retracting the steerable wheel intoa compartment in the vehicle, wherein the mechanism comprises a pillarpivotally mounted to the vehicle within the compartment, a steering armconnected to rotate the pillar about its own axis, a collar slidablymounted on the pillar but rotationally fixed relative thereto, the wheelbeing attached to the collar so that it can be raised and lowered in useby sliding the collar on the pillar and steered by movement of thesteering arm to rotate the pillar.

Arrangement can be made for the wheels to be steered in any position ofthe collar on the pillar.

Preferably the pillar and collar are of cooperating non-circular sectionso that rotation of the pillar automatically moves the collar withoutthe use of keyways, splines, or guides. Advantageously the collarsupports a pair of wheels. In an amphibious craft these may be arrangedone on each side of the longitudinal centre line of the craft. Usuallythe steerable wheel will be attached to the collar via wheel supports.

In one embodiment the orientation of the wheel supports is altered froman upright position when the wheel is in the lowered position to asubstantially horizontal position when the wheel is raised for stowage.

The invention will now be described, by way of example, with referenceto the accompanying drawings in which:

FIG. 1 is a side view of an amphibious craft according to the inventionhaving a profile with a deep-V configuration,

FIG. 2 is a schematic section view in plan of the craft of FIG. 1

FIG. 3 is a schematic front section showing one embodiment of a frontwheel retraction mechanism and

FIGS. 4a, 4b, 4c, and 4d, are schematic partial views of a secondretraction mechanism for the front wheels.

The drawings illustrate an amphibious craft in the form of a boat havinga hull with a deep-V cross-section below the water line. The boat isconvertible so as to provide a means of driving the boat on land onwheels. The operation of the boat in water is substantially unimpairedother than due to the extra weight carried. The profile is unaltered andthe drag is not substantially increased.

The boat in water is driven either by a large inboard motor normally inan aft position (such as shown at Y in FIG. 2) or by an outboard motor(not shown). Where an inboard motor is used it could also power thewheels for use of the craft on land. If an outboard motor is used on theboat, a secondary motor such as that shown at X would have to beprovided to drive the wheels. In either case the boat wheels are drivenin a manner similar to those on an automobile through a gear box G, ashaft 8, a differential 14 and a shaft 15. Inboard brakes 10 would alsobe provided.

The wheels on the boat comprise a pair of steerable forward or frontwheels 11 designed to carry one third of the weight of the boat and setone either side of a keel 12 in the bow of the boat; and two drivablerear wheels 13 designed to carry two thirds of the weight of the bolt.The rear wheels 13 are positioned on opposed sides of the boat insidethe line of the hull. The use of a pair of forward wheels leaves thekeel undisturbed and so does not interfere with the strength of the boatstructure.

The operation of the rear wheels is described and claimed in myco-pending PCT application No 89/10854 of the same date.

The steerable wheels 11 are supported by stub axles 21a mounted on aforked wheel support or "forks" 21. The upper end of the forked wheelsupport 21 is in the form of a square-sectioned collar 22. The collar 22is slidably mounted on a square-sectioned, rectangular or other corneredsection central pillar 23, the upper and lower ends of which pillar arepivotally mounted to the boat structure at 24 and 25. The pillar 23 ispivoted to steer the craft on land by movement of a steering arm 26which action turns the collar 22 to turn the wheels 11. When the wheelsare in the lowered position they can be held in position by securitylocks (not shown). The wheels are raised and lowered by a hydraulic ram(not shown in FIG. 3) which operates between respective brackets on thepillar and collar. The pillar, the collar and the ram form elements of aretraction mechanism for the wheels. In the raised position the wheelsare stowed in a compartment 20 in the bow of the boat. The fitting ofthe compartment to the hull is entirely watertight so that waterentering the compartment does not enter the boat. When the compartmentis closed the profile of the boat is maintained by two doors 27 hingedat 28 which are closed against the bottom 29 of the boat, but need notbe watertight. The top of the compartment is situated well above thewater line and therefore any water seeping past the doors will remain inthe compartment at a level equal to or below the water level outside thehull. The actual portion of the bottom of the boat that is cut away toform the doors 27 is important as sufficient room must be left for thewheel "forks" 21 to turn the wheels in the lowered position withoutcollision or interference with or from the boat structure.

The arrangement of the steering arm above the water line of the boatmakes for a simpler mechanism. Moreover with this sliding collararrangement the wheels can be steered successfully in any position ofthe collar on the pillar. The steering for the boat is not moveable withthe wheel but instead stays in one place.

In some boats there may not be sufficient room for a large steerablewheel compartment with the wheel "forks" 21 stored substantiallyvertically. FIG. 4 shows an alternative arrangement to cater for storagein a smaller deck to keel depth. Each drawing shows only part of thearrangement and it may be necessary to refer to FIG. 3 to understand thewhole.

FIG. 4a is a front view of the lower part of the mechanism showing thewheel forks 21 and one wheel 11. The wheel "forks" 21 are pivotallymounted at 31 to the collar 22 and are connected together by a bar 32.Respective bars 33 are pivotally mounted to opposed sides of the bar 32at one end and at the other end 30 are pivotally mounted to opposedsides of the central pillar 23. A shoulder 34 on the collar 22 providesa lower mounting point for the ram now shown at 35 and the pivotalmounting 25 of the central pillar 23 to the keel 12 is also shown. Ifdesired the section of the keel on which the pillar is mounted can beremoved and replaced by an equivalent section of different andpreferably stronger material from the rest of the keel, such as acasting or fabrication. The movement of the collar up and down thepillar in either embodiment can equally be controlled by any suitablealternative to hydraulic rams, such as screw, cables, chain, compressedair etc. Slots can be machined into the pillar to allow the moving forceto be applied from inside if desired for example by an internal ballscrew.

FIG. 4b is a side view of FIG. 4a showing the central area of themechanism with the wheels in the lowered position. It will be noted thatas the ram 35 draws the collar 22 up until it abuts the pivotal mounting30 the pivoted bars operate as a lever mechanism to lift the wheelsuntil the "forks" 21 lie along the line of the boat substantiallyhorizontally.

FIG. 4c illustrates the connection of the central pillar 23 at the upperend of the pillar. The same pivotal connection and height adjustmentpieces and fillers may be used at the lower pivotal mounting 25. Theconnection comprises a sub-assembly of a mounting block 36, a thrustbearing 37 and a nut 41. The upper race of the thrust bearing 37 has apivot mounting 38 for attachment to the deck. The lower race of thebearing 38 is located by a threaded bolt portion 39. The bolt 39 isthreaded through the centre of the mounting block 36 and is screwthreaded into the nut 41. This sub-assembly is then fitted into the topend of the pillar 23 to which it is bolted via holes 43 in the block and44 in the pillar. The length of the pillar 23 is selected in accordancewith the distance between the deck and the keel on any particular boatand any fine adjustment to the fitting is achieved using shims (notshown).

In each case the hydraulic ram or rams are connected to a hydraulic pumppowered by the motor X or Y or an electrically powered pump. Thehydraulic ram 35 is operable from a remote position in the cockpit ofthe vehicle to raise or lower the wheels by the required amountinstantly. The steering is also operable by remote control from thecockpit, the wheels being steerable throughout the height range. Thesteering arm 26 and levers connecting the steering arm to the remotesteering mechanism in the cockpit have constant geometry with the anglesonly changing in one plane. If the craft is not expected to travel atmore than 25 miles per hour on land, floatation tires can be usedabsolving the need for suspension. If a greater land speed is requiredthen higher pressure road tires will be needed and some springing orother suspension.

Both embodiments could accommodate suspension. This would be interposedbetween the sliding collar and the mechanism for moving the collar upand down the pillar. The front wheel could be driven by a motor mountedon the collar or the pillar, or remote from the pillar through chains orshafts to the wheels. Hydraulic drive to the wheels themselves could beused. Although the retractable wheels are described in relation to anamphibious craft it will be appreciated that the same mechanism could beused in other applications.

I claim:
 1. A vehicle having a steerable wheel or pair of wheels and amechanism for retracting the steerable wheel or pair of wheels into acompartment in the vehicle, wherein the mechanism comprises a pillarpivotally mounted to the vehicle within the compartment, a steering armconnected to rotate the pillar about its own axis, a collar slidablymounted on the pillar but rotationally fixed relative thereto, thesteerable wheel or pair of wheels being attached to the collar so thatthe steerable wheel or pair of wheels can be raised and lowered in useby sliding the collar on the pillar and steered by movement of thesteering arm to rotate the pillar.
 2. A vehicle according to claim 1wherein the pillar and collar are of cooperating noncircular section sothat rotation of the pillar automatically moves the collar about thesame axis.
 3. A vehicle according to claim 1 in which the pillar hasupper and lower ends, wherein the pillar is mounted to the vehicleadjacent the upper and lower ends of the pillar.
 4. A vehicle accordingto claim 3 wherein the upper and lower mounting of the pillar to thevehicle comprise pivotal mountings to the top and bottom of the pillarabout transverse axes.
 5. A vehicle according to claim 1 wherein thevehicle is an amphibious craft in the shape of a boat having a hull witha hull profile.
 6. A vehicle according to claim 5 wherein the hullprofile has a deep-V configuration.
 7. A vehicle according to claim 6wherein the collar supports a pair of steerable wheels disposed onopposite sides of the longitudinal centre line of the boat.
 8. A vehicleaccording to claim 7 wherein said wheels are mounted on respective stubaxles carried by respective forks of a forked wheel support attached tothe collar.
 9. A vehicle according to claim 8 wherein the wheel supportis attached to the collar via a first pivotal mounting and the mechanismincludes a system of linkages which operate to raise and lower thewheels by converting a sliding action of the collar on the pillar to apivotal movement of the wheel support with respect to the pillar aboutthe pivotal mounting.
 10. A vehicle according to claim 9 wherein thesystem of linkages includes a link between a second pivotal mountingpoint on the pillar and a third pivotal mounting point on the wheelsupport spaced from the first pivotal mounting.
 11. A vehicle accordingto claim 9 wherein the wheels are lowered and retracted by anextension/contraction device connected between the pillar and thecollar.
 12. A vehicle according to claim 5 wherein the steering arm isfixed to the upper end of the pillar.
 13. A vehicle according to claim 5wherein the collar supports a pair of steerable wheels disposed onopposite sides of the longitudinal centre line of the boat.
 14. Avehicle according to claim 13 wherein the wheel support is attached tothe collar va a first pivotal mounting and the mechanism includes asystem of linkages which operate to raise and lower the wheels byconverting a sliding action of the collar on the pillar a pivotalmovement of the wheel support with respect to the pillar about thepivotal mounting.
 15. A vehicle according to claim 14 wherein the systemof linkages includes a link between a second pivotal mounting point onthe pillar and a third pivotal mounting point on the wheel supportspaced from the first pivotal mounting.
 16. A vehicle according to claim14 wherein the wheels are lowered and retracted by anextension/contraction device connected between the pillar and thecollar.